Salesforce CPQ: MDQ Segment Subtotals Do Not Match Quote Total When "Line Subtotals Total Field" Is Configured as Customer Total

Customers may notice the following behaviour:

1. MDQ segment subtotals displayed in the Quote Line Editor are higher than expected.
2. The subtotal displayed for segmented products does not match the overall Quote Total.
3. The discrepancy is observed even in environments without customizations, automation, or price rules.
4. The issue can be reproduced consistently with MDQ products when using Customer Total as the Line Subtotal field.

Steps to Reproduce:
1. Navigate to: Installed Packages → Salesforce CPQ → Configure
2. Under Line Editor Settings:
       Set Line Subtotals Total Field = Customer Total
       Leave Totals Field as the default (typically Net Total)
3. Create an MDQ Product:
      Subscription Pricing = Fixed
      Subscription Term = 12
      Active = True
      Add a Standard Price
      Add a Price Dimension
         Type = Year
4. Create an Opportunity.
5. Create a Quote:
      Primary = True
      Start Date = Current Date
      Subscription Term = 24 (or greater)
6. Edit Lines.
7. Add the MDQ Product to the Quote.
8. Update quantities across multiple segments (Year 1, Year 2, etc.).
9. Save and calculate the Quote.
10. Observe:
      Segment Subtotals displayed in the Quote Line Editor.
      Overall Quote Total displayed at the bottom of the editor.

Root Cause:
Salesforce CPQ calculates these values using different calculation paths:

Quote Total
  Uses the field configured under Totals Field.
  Typically references Net Total.
  Represents the final calculated price after all pricing waterfall calculations.

Segment Subtotal
  Uses the field configured under Line Subtotals Total Field.
  When configured as Customer Total, CPQ calculates the subtotal using: Customer Total × Effective Quantity